The present invention generally relates to measuring video noise levels, and more particularly to measuring noise levels of digital video signals and the further processing the video signals based on the measured noise.
Digitally formatted video signals have proliferated the past several years with the rise in popularity of satellite television, DVD players, and other digital video sources. The digital conquest is almost complete, with analog video nearly relegated to an issue of backward compatibility.
At the same time, these signals are being processed by increasingly complex digital systems and integrated circuits. Examples of integrated circuits capable of tremendous amounts of video processing are those designed and developed by NVIDIA Corporation of Santa Clara, Calif. These powerful NVIDIA devices include myriad circuits such as processors for 2-D and 3-D graphics, as well as video.
While digital video signals processed by an NVIDIA device are stunningly vivid, their input video signals can be corrupted by video noise. Sources of this noise include power supply noise, transmission errors, signal coupling, and others. It is therefore desirable to use some of the abundant processing power of these NVIDIA devices to reduce video noise or to improve video images in other ways.
The first step in handling video noise is to make an accurate measurement of the video noise level. Once the amount of noise present in a video signal is known, a decision regarding how to proceed can be made.
Video images are made up of a series of frames that are viewed in rapid succession on a monitor or other type of display apparatus. Conventional solutions compare a previous frame to a current frame in order to make a noise determination. But this requires accessing previous frames, so implementing it greatly increases the number of memory accesses and reduces the memory bandwidth available for other purposes.
Accordingly, what is needed are circuits, methods, and apparatus for improving video noise level measurements. It is also desirable that these measurements be made using only a current frame.